Jian-Wen Wang

Quantum Design for Advanced Qubits

  1. Feng-Ming Liu,
  2. Ming-Cheng Chen,
  3. Can Wang,
  4. Shao-Wei Li,
  5. Zhong-Xia Shang,
  6. Chong Ying,
  7. Jian-Wen Wang,
  8. Cheng-Zhi Peng,
  9. Xiaobo Zhu,
  10. Chao-Yang Lu,
  11. and Jian-Wei Pan
Simulations of high-complexity quantum systems, which are intractable for classical computers, can be efficiently done with quantum computers. Similarly, the increasingly complex quantum
electronic circuits themselves will also need efficient simulations on quantum computers, which in turn will be important in quantum-aided design for next-generation quantum processors. Here, we implement variational quantum eigensolvers to simulate a Josephson-junction-array quantum circuit, which leads to the discovery of a new type of high-performance qubit, plasonium. We fabricate this new qubit and demonstrate that it exhibits not only long coherence time and high gate fidelity, but also a shrinking physical size and larger anharmonicity than the transmon, which can offer a number of advantages for scaling up multi-qubit devices. Our work opens the way to designing advanced quantum processors using existing quantum computing resources.
arxiv pdf

Demonstration of Adiabatic Variational Quantum Computing with a Superconducting Quantum Coprocessor

  1. Ming-Cheng Chen,
  2. Ming Gong,
  3. Xiao-Si Xu,
  4. Xiao Yuan,
  5. Jian-Wen Wang,
  6. Can Wang,
  7. Chong Ying,
  8. Jin Lin,
  9. Yu Xu,
  10. Yulin Wu,
  11. Shiyu Wang,
  12. Hui Deng,
  13. Futian Liang,
  14. Cheng-Zhi Peng,
  15. Simon C. Benjamin,
  16. Xiaobo Zhu,
  17. Chao-Yang Lu,
  18. and Jian-Wei Pan
Adiabatic quantum computing enables the preparation of many-body ground states. This is key for applications in chemistry, materials science, and beyond. Realisation poses major experimental
challenges: Direct analog implementation requires complex Hamiltonian engineering, while the digitised version needs deep quantum gate circuits. To bypass these obstacles, we suggest an adiabatic variational hybrid algorithm, which employs short quantum circuits and provides a systematic quantum adiabatic optimisation of the circuit parameters. The quantum adiabatic theorem promises not only the ground state but also that the excited eigenstates can be found. We report the first experimental demonstration that many-body eigenstates can be efficiently prepared by an adiabatic variational algorithm assisted with a multi-qubit superconducting coprocessor. We track the real-time evolution of the ground and exited states of transverse-field Ising spins with a fidelity up that can reach about 99%.
arxiv pdf